/**
 * --------------------------------------------------------------------------
 * Bootstrap (v4.3.1): scrollspy.js
 * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
 * --------------------------------------------------------------------------
 */

import $ from 'jquery'
import Util from './util'

/**
 * ------------------------------------------------------------------------
 * Constants
 * ------------------------------------------------------------------------
 */

const NAME = 'scrollspy'
const VERSION = '4.3.1'
const DATA_KEY = 'bs.scrollspy'
const EVENT_KEY = `.${DATA_KEY}`
const DATA_API_KEY = '.data-api'
const JQUERY_NO_CONFLICT = $.fn[NAME]

const Default = {
    offset: 10,
    method: 'auto',
    target: ''
}

const DefaultType = {
    offset: 'number',
    method: 'string',
    target: '(string|element)'
}

const Event = {
    ACTIVATE: `activate${EVENT_KEY}`,
    SCROLL: `scroll${EVENT_KEY}`,
    LOAD_DATA_API: `load${EVENT_KEY}${DATA_API_KEY}`
}

const ClassName = {
    DROPDOWN_ITEM: 'dropdown-item',
    DROPDOWN_MENU: 'dropdown-menu',
    ACTIVE: 'active'
}

const Selector = {
    DATA_SPY: '[data-spy="scroll"]',
    ACTIVE: '.active',
    NAV_LIST_GROUP: '.nav, .list-group',
    NAV_LINKS: '.nav-link',
    NAV_ITEMS: '.nav-item',
    LIST_ITEMS: '.list-group-item',
    DROPDOWN: '.dropdown',
    DROPDOWN_ITEMS: '.dropdown-item',
    DROPDOWN_TOGGLE: '.dropdown-toggle'
}

const OffsetMethod = {
    OFFSET: 'offset',
    POSITION: 'position'
}

/**
 * ------------------------------------------------------------------------
 * Class Definition
 * ------------------------------------------------------------------------
 */

class ScrollSpy {
    constructor(element, config) {
        this._element = element
        this._scrollElement = element.tagName === 'BODY' ? window : element
        this._config = this._getConfig(config)
        this._selector = `${this._config.target} ${Selector.NAV_LINKS},` +
            `${this._config.target} ${Selector.LIST_ITEMS},` +
            `${this._config.target} ${Selector.DROPDOWN_ITEMS}`
        this._offsets = []
        this._targets = []
        this._activeTarget = null
        this._scrollHeight = 0

        $(this._scrollElement).on(Event.SCROLL, (event) => this._process(event))

        this.refresh()
        this._process()
    }

    // Getters

    static get VERSION() {
        return VERSION
    }

    static get Default() {
        return Default
    }

    // Public

    refresh() {
        const autoMethod = this._scrollElement === this._scrollElement.window ?
            OffsetMethod.OFFSET : OffsetMethod.POSITION

        const offsetMethod = this._config.method === 'auto' ?
            autoMethod : this._config.method

        const offsetBase = offsetMethod === OffsetMethod.POSITION ?
            this._getScrollTop() : 0

        this._offsets = []
        this._targets = []

        this._scrollHeight = this._getScrollHeight()

        const targets = [].slice.call(document.querySelectorAll(this._selector))

        targets
            .map((element) => {
                let target
                const targetSelector = Util.getSelectorFromElement(element)

                if (targetSelector) {
                    target = document.querySelector(targetSelector)
                }

                if (target) {
                    const targetBCR = target.getBoundingClientRect()
                    if (targetBCR.width || targetBCR.height) {
                        // TODO (fat): remove sketch reliance on jQuery position/offset
                        return [
                            $(target)[offsetMethod]().top + offsetBase,
                            targetSelector
                        ]
                    }
                }
                return null
            })
            .filter((item) => item)
            .sort((a, b) => a[0] - b[0])
            .forEach((item) => {
                this._offsets.push(item[0])
                this._targets.push(item[1])
            })
    }

    dispose() {
        $.removeData(this._element, DATA_KEY)
        $(this._scrollElement).off(EVENT_KEY)

        this._element = null
        this._scrollElement = null
        this._config = null
        this._selector = null
        this._offsets = null
        this._targets = null
        this._activeTarget = null
        this._scrollHeight = null
    }

    // Private

    _getConfig(config) {
        config = {
            ...Default,
            ...typeof config === 'object' && config ? config : {}
        }

        if (typeof config.target !== 'string') {
            let id = $(config.target).attr('id')
            if (!id) {
                id = Util.getUID(NAME)
                $(config.target).attr('id', id)
            }
            config.target = `#${id}`
        }

        Util.typeCheckConfig(NAME, config, DefaultType)

        return config
    }

    _getScrollTop() {
        return this._scrollElement === window ?
            this._scrollElement.pageYOffset : this._scrollElement.scrollTop
    }

    _getScrollHeight() {
        return this._scrollElement.scrollHeight || Math.max(
            document.body.scrollHeight,
            document.documentElement.scrollHeight
        )
    }

    _getOffsetHeight() {
        return this._scrollElement === window ?
            window.innerHeight : this._scrollElement.getBoundingClientRect().height
    }

    _process() {
        const scrollTop = this._getScrollTop() + this._config.offset
        const scrollHeight = this._getScrollHeight()
        const maxScroll = this._config.offset +
            scrollHeight -
            this._getOffsetHeight()

        if (this._scrollHeight !== scrollHeight) {
            this.refresh()
        }

        if (scrollTop >= maxScroll) {
            const target = this._targets[this._targets.length - 1]

            if (this._activeTarget !== target) {
                this._activate(target)
            }
            return
        }

        if (this._activeTarget && scrollTop < this._offsets[0] && this._offsets[0] > 0) {
            this._activeTarget = null
            this._clear()
            return
        }

        const offsetLength = this._offsets.length
        for (let i = offsetLength; i--;) {
            const isActiveTarget = this._activeTarget !== this._targets[i] &&
                scrollTop >= this._offsets[i] &&
                (typeof this._offsets[i + 1] === 'undefined' ||
                    scrollTop < this._offsets[i + 1])

            if (isActiveTarget) {
                this._activate(this._targets[i])
            }
        }
    }

    _activate(target) {
        this._activeTarget = target

        this._clear()

        const queries = this._selector
            .split(',')
            .map((selector) => `${selector}[data-target="${target}"],${selector}[href="${target}"]`)

        const $link = $([].slice.call(document.querySelectorAll(queries.join(','))))

        if ($link.hasClass(ClassName.DROPDOWN_ITEM)) {
            $link.closest(Selector.DROPDOWN).find(Selector.DROPDOWN_TOGGLE).addClass(ClassName.ACTIVE)
            $link.addClass(ClassName.ACTIVE)
        } else {
            // Set triggered link as active
            $link.addClass(ClassName.ACTIVE)
            // Set triggered links parents as active
            // With both <ul> and <nav> markup a parent is the previous sibling of any nav ancestor
            $link.parents(Selector.NAV_LIST_GROUP).prev(`${Selector.NAV_LINKS}, ${Selector.LIST_ITEMS}`).addClass(ClassName.ACTIVE)
            // Handle special case when .nav-link is inside .nav-item
            $link.parents(Selector.NAV_LIST_GROUP).prev(Selector.NAV_ITEMS).children(Selector.NAV_LINKS).addClass(ClassName.ACTIVE)
        }

        $(this._scrollElement).trigger(Event.ACTIVATE, {
            relatedTarget: target
        })
    }

    _clear() {
        [].slice.call(document.querySelectorAll(this._selector))
            .filter((node) => node.classList.contains(ClassName.ACTIVE))
            .forEach((node) => node.classList.remove(ClassName.ACTIVE))
    }

    // Static

    static _jQueryInterface(config) {
        return this.each(function() {
            let data = $(this).data(DATA_KEY)
            const _config = typeof config === 'object' && config

            if (!data) {
                data = new ScrollSpy(this, _config)
                $(this).data(DATA_KEY, data)
            }

            if (typeof config === 'string') {
                if (typeof data[config] === 'undefined') {
                    throw new TypeError(`No method named "${config}"`)
                }
                data[config]()
            }
        })
    }
}

/**
 * ------------------------------------------------------------------------
 * Data Api implementation
 * ------------------------------------------------------------------------
 */

$(window).on(Event.LOAD_DATA_API, () => {
    const scrollSpys = [].slice.call(document.querySelectorAll(Selector.DATA_SPY))
    const scrollSpysLength = scrollSpys.length

    for (let i = scrollSpysLength; i--;) {
        const $spy = $(scrollSpys[i])
        ScrollSpy._jQueryInterface.call($spy, $spy.data())
    }
})

/**
 * ------------------------------------------------------------------------
 * jQuery
 * ------------------------------------------------------------------------
 */

$.fn[NAME] = ScrollSpy._jQueryInterface
$.fn[NAME].Constructor = ScrollSpy
$.fn[NAME].noConflict = () => {
    $.fn[NAME] = JQUERY_NO_CONFLICT
    return ScrollSpy._jQueryInterface
}

export default ScrollSpy